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Mold Growth on Window Sills: Causes and Prevention

The presence of mold on window sills can cause many problems, including stains and compromised window life span. It can also trigger allergies and other respiratory illnesses. In this blog, local window and door replacement company  Renewal by Andersen® of Southwest Missouri shares a look at the things that you can do to prevent mold growth on window sills.Mold Growth on Window Sills: Causes and Prevention
What Causes Mold Growth on Window Sills?

High moisture levels are conducive to mold growth, which is why it thrives in humid areas such as basements, bathrooms, and attics. Moisture that comes from indoor condensation and humid outside air usually collect at the window sill, and doesn’t immediately dry out.

Exposed wood may also absorb and retain moisture. Sometimes these areas are blocked by window treatments, which would then allow mold to grow undisturbed and hidden from view. Certain types of mold, particularly black mold, are notoriously difficult to remove, even on the best vinyl replacement windows on the market.

The Effects of Mold

We have mentioned how the presence of mold can affect the respiratory system in both children and adults. To elaborate, some people have sensitivity to mold spores, and may develop stuffy nose, coughing, and throat irritation when exposed to high levels mold spores in the air. Skin and eye irritation may accompany these symptoms. Certain types of allergies may also be triggered by mold. A 2004 study conducted by the Institute of Medicine presents evidence that links exposure to mold indoors with asthma, hypersensitivity pneumonitis, and other upper respiratory problems.

How to Prevent Mold Growth on Window Sills

While you can’t completely eliminate mold spores from getting into your home, there are some things that you can do to prevent mold growth on window sills, as well as in other parts of your home:

Maintain Relative Indoor Humidity — Humidity levels change depending on the season: it’s dry during winter and humid during summer. A home humidifier/dehumidifier helps maintain indoor humidity relative to outdoor levels by releasing or absorbing moisture as needed, preventing window condensation and other issues that can lead to mold growth.

Allow Regular Ventilation — Opening your windows for at least 15 minutes a day helps flush out indoor air pollutants, including mold spores. You should also make sure that the air filters in your home ventilation system are replaced when full.

Regularly Clean Your Windows — Make it a point to clean your windows twice a year. Low-maintenance windows with easy cleaning features such as removable or tiltable sashes make this task easier and safer. Make sure that the window treatments are likewise cleaned.

Renewal by Andersen of Southwest Missouri is your leading provider of popular window styles, including double hung replacement windows. Give us a call at (417) 268-9301 or fill out our contact form to schedule an appointment.


"Excellent service and product! They checked in with me every few weeks while we were waiting for the order. I was impressed with Sam, who measured my windows and headed the installation crew. He was respectful and patient with his team. They cleaned up after themselves. Before the new windows I had huge windows that didn’t open. Now I feel much safer and get better temperatures in those rooms."

Kimberly Kester
Jul 18, 2022

"My experience with Anderson Renewal was amazing! From the first meeting with Miranda to choose my windows and doors to the installation provided by Tim and his crew was a pleasure! I just bought a home built in the 1960's that needed new windows and a new double front door with sidelights. As everyone knows Anderson Windows are great, but it was the people I interacted with from Anderson that made it such a great experience. It took three days for the windows and door to be installed and they "worked" every minute they were here. My huge front door took most of the day to install because they had to put in a new header and other improvements to make it fit! They even put up new drywall on the inside. Many people in the neighborhood have stopped by to comment on my beautiful front door! I think the crew left my house cleaner than it was before they started! Constantly cleaning up after themselves. I am thrilled with my windows and feel lucky to have met the team at Anderson."

Kimberly Wilson
Jul 17, 2022

"Very professional staff . No pressure sales. The job they do is neat and clean, no cleanup left for the owner. Communication is great. Always informed on the status of of your product, AND the tin of cookies you receive afterwards is a pleasant plus."

Peggy Spivy Morse
Jul 13, 2022

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